Sheet-metal piston



A. v. POURROY SHEET METAL PISTON Filed April 6, 192.2

l1 N m i1 WWW a /5\ I E! MIIN- IIH l \ll llllll' 9 7 1111 l I l mu H1 11v VEN TOR. Armand l/ Paw/0y BYWM- M ATTORNEY Patented Get. 28, 1924.,

ABM-AND v. rounRoY, or OAKLAND, cnmronmn.

SHEET-METAL PISTON.

Application filed April 6,

To all whom it may concern:

Be, it known that I, ARMAND V. POURROY,

a citizen of the United States, residin at 2914 East'l9th Street, in the city of a e land, county of Alameda, and State of California, have invented a new and useful Sheet-Metal Piston, of which the following is a specification.

My invention relates in general to pistons, and more particularly to a lightweight, removable-shell piston for the internal-combustion engine of the ordinary motor vehicle in common use.

Heretofore the usual types of pistons known to me, have been made of cast iron, cast aluminum, or other cast material, cast in a single piece. This necessitated machining the casting very carefully to insure the proper size, smoothness and polishability, and also to insur the proper functioning of those parts integral with the piston, particularly the wrist pin. Difiiculty has been experienced with pistons made of cast iron, due to their excessive weight and tendency to.wear unevenly andbecome out-of-round, necessitating replacing the piston with a new one. Difficulty has also been experienced with pistons made of cast aluminum and other alloys, due to their lack of me- 3 chanical strength, their tendency to excessive expansion, their inability to take a polished surface, and to their lack of resistance to wear and tendency to become out-ofround, necessitating replacing the piston with a new one. Difiiculty has also been experienced in the present type of piston, due to the wrist pin creeping from its normal position and scoring the cylinder walls.

Therefore, the principal objects of my invention, are: to overcome the above difliculties by the provision of a built-up piston, comprising an external shell of sheet metal possessing wearing qualities and an interior cast aluminum or other alloy frame. In my piston is gained, lightness combined with resistance to wear, chea ness of manufacture, means for securing t e Wrist pin in a full floating position in conjunction with 1922. Serial'No. 549,985.

I which:

Figure 1 is a sectional elevation of my piston, the Wrist pin and bolt being shown in full.

Fii 2 is a similar elevation, taken on the line A of Fig. 1.

Fig. 3 is a plan view of Fig. 1 with the shell and bolt removed.

Fig. 4 is a cross sectional view of Fig. 2, taken on the line B-B with the shell removed, and looking in the direction of the arrows.

Fig. 5 is an elevation similar to Fig. 1, and 1s a part of a modified form of the iston and shows the frame secured to the s ell by more than one bolt.

Briefly expressed, my invention is a piston in the form of a built-up structure, and comprises an interior frame of cast alumi- ,num or other light-weight alloy, having the customary bosses for the support of the wrist pin, a removable exterior shell of sheet metal formed from a single sheet with recesses thereon for the reception of piston rings, and means for securing the shell to the frame, whereby the wrist pin is supported in a full-floating position and without lateral movement.

A detailed description of'the illustrated embodiment of my invention-follows:

Referring to the drawings, the shell 1 is preferably formed of sheet steel and has an opening at one end and is closed at the other end, the closed end may be dished as illustrated and the open end provided with an annular flange 2 to gain structural strength. The shell has ring grooves 3 formed thereon a emma near the closed end for the reception of piston rings, and a wider groove 4: near the open end, forming a walled flange 5 for the purpose of centering and snugly retaining the ring-beset of the frame in position.

The frame is preferably made of cast aluminum or other light-weight alloy, and is adapted to slip into position in the shell and be securely bolted thereto by bolt '2 and nut 8, the nut being locked in position by cotter pin 9 suitably disposed in one of the grooves 10 in the nut.

The shell and the frame are both so proortioned that when bolted together, the lioss, 11 on the frame top fits against the closed end of shell, and the ring-base 6 of the frame is contiguous to the annular flange 5 of the shell.

The frame is basket-like in structure and has a disc-like or umbrella top 12 surmounted by boss 11, and a tubular or ring-base 6 provided with a pair of bosses 13 diametrically opposed, the top and base being connected by arms 14; which terminate in the ring bosses. The diameter of the top 12 is slightly less than that of the ring-base '6, as it is preferably desired that the only circumferential machine finish of the frame shall be that of the ring-base.

The rin -base may have one or more slits 15 cut through its wall to relieve the excess stresses of the piston due to heat expansion in service.

The umbrella top also functions as a protector for the top or closed end of the shell, by preventing the splashing of oil against the explosion wall of the piston.

Efl'ective heat radiation is also a feature of advantage with my type of piston, as the entire inner surface of the piston shell is substantially in contact with the air, thus increasing the efiiciency of the engine to a marked degree.

From the drawing, it is evident that the Wrist pin 16 would necessarily have to be in its proper position before the assembling of the shell with the frame, and it is also evident that the wrist pin cannot become engaged with, and score the walls of the cylinder within which the piston inigl-it be moving, as the wrist pin is prevented from lat eral movement by the annular flange 5 of the shell the wrist pin does not have to be se- H cure in place by any of the methods usually employed, and is, in fact, full-floating in action.

In the modification of my invention shown in Fig. 5, the head of the shell is flat instead of bumped as in Fig. 1, and the frameis secured to it by a plurality of bolts. In some cases, ll may prefer to use this type of construction.

While T have shown and described my invention in detail, I do not wish to be limited to the invention precisely as illustrated, but

wish to include all variations of it that come within the spirit and scope of the invention as claimed.

What ll claim as new and desire to secure by Letters Patent is: 7

1. lln a. piston, a single-piece shell provided with narrow ring grooves near its top, and a wide ring groove below said narrow ring grooves, the internal peripheral surface of said wide groove forming a bearingwall.

2. ln a piston, a sheet metal shell formed with narrow ring grooves near its top, and a wide ring groove toward its bottom, the latter groove provided for reinforcement and hearing means.

3. In a piston, a cast frame of basket-like construction provided with a disc-liketop and a ring-base, the central area of said top and the outside circumferential area of said it base being contact surfaces, for engagement with the shell member of the piston, and said ring-base provided with a slit for pansion relief.

4. ln 2. piston, a cast frame having an um W brella top and a ring-base, and having formed therebetween a pair of arms diametrically opposed, each arm terminating in a boss on the ring-base, the said top and said bosses provided with holes for the reception of supporting means, the said arms being the only means connecting said top to said base, thus permitting effective heat radiation from the piston.

5. lln a piston. in combination with a sheetmetal shell, a basket-shaped interior frame having a bossed-top and a bossed-ring-base and connecting arm members therebetween, said bossed parts provided with supporting elements.

6. A piston, comprising a cupped, singlepiece grooved sheet metal shell and a metallic basket-like frame of basket form adapted to fit within the shell and be removably secured thereto.

7. A piston, comprising a sheet metal external shell and a cast internal frame of basket form having a disc-like top and a ring-base, the said top adapted to engage the shell top and the said base adapted to engage the wall of the shell, and the body of the frame spaced from the shell for efi'ective heat radiation.

8. A piston, comprising a sheet metal ex ternal shell and a cast internal frame, the latter having a disc-like top and a ring-base. the said top adapted to engage the shell top and the said base adapted to engage the wall of the shell, the ring of said ring-base be ing slotted for expansion relief.

9. A piston, comprising a grooved external sheet metal shell, an internal frame and a wrist pin; the latter adapted to be floatably supported in the frame, and said frame provided with means for detach'ably securing 1 rename shel of continuous surface and a ed for engagement with the shell grooves, and the wrist pin ada ted for engagement with the frame, the sai wearing shell adapted for replacement on said frame, the shell enveloping the frame and the contained pin, thereby locking the pin in position but allowing the same to float in rotation.

ARI) V. POURROY.

mg one to the other, the piston ringsadapb 

